Conventionally, a process unit having a main unit and a toner cartridge mountable on the main unit is known.
A main unit includes a photosensitive drum and a developing unit. The developing unit includes a developing roller. The developing unit has an opening for receiving a toner supplied from a toner cartridge. The toner cartridge has an opening for discharging a toner in the inside. The opening of the toner cartridge faces the opening of the developing unit in a state where the toner cartridge is mounted on the main unit. The toner cartridge includes a shutter that is movable between an open position in which the opening is opened, and a closed position in which the opening is closed. The shutter is moved between the open position and the closed position by operation by a user, in a state where the toner cartridge is mounted on the main unit.